Remove Tensor and Hamiltonian in python frontend for lightning (#994)

We are removing the Tensor and Hamiltonian classes, so we should remove
their (minimal) remaining references in the Lightning python code.

Blocks running CI for the [PL PR
legacy_opmath, since every test that uses `lightning.qubit` fails with
Tensor removed.

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Co-authored-by: ringo-but-quantum <[email protected]>

Author: 2 people

pennylane_lightning/core/_version.py

@@ -17,4 +17,4 @@
 """
 
 
-__version__ = "0.40.0-dev9"
+__version__ = "0.40.0-dev8"